DENVER -- Even in a relief role, Chris Volstad turned out being the Marlins' much-needed stopper on Sunday afternoon.

Volstad tossed two scoreless innings in his big league debut, and backed by Cody Ross' five RBIs, the 21-year-old helped the Marlins salvage the series finale with the Rockies, 10-5, in front of 27,167 at Coors Field.

After being frustrated for three straight games in Colorado, the Marlins took Game 4 in the series. Ross provided the offensive punch, with a two-run single and a two-run homer off Rockies All-Star Aaron Cook.

But the big boost came from Volstad, the first-round pick in 2005, who was called up from Double-A Carolina on Sunday morning. Projected to be a starter, he appeared in relief in the fifth and six innings, taking over for Mark Hendrickson, who gave up four runs in four innings.

"I found out last night about 11," Volstad said of when he got the call. "I flew out [of Raleigh, N.C.] at 6 in the morning. I got here with enough time to play catch and get out to the bullpen.

"It's just starting to sink in right now. Before the game, I didn't have time to get nervous or anything. I went right to the game."

In the four games, Ross went 12-for-20 (going 3-for-5 on Sunday) and he collected 15 RBIs.

"It's just one of those things, when you're hot you're hot, and when you're cold, you're cold," Ross said. "I've been cold, at the beginning of the season. I'm finally starting to turn it around. I'm trying to help this team win.

"Today was a big victory for us after the three tough losses that we took from these guys. You've got to give him credit. They battled. They're resilient. They kept scoring runs. We never stopped, either."

The way Ross hit over the past four games, a number of Marlins teammates joked that Rockies manager Clint Hurdle, who is managing the National League All-Star team, is adding Ross to his Midsummer Classic roster.

After the game, Marlins manager Fredi Gonzalez announced that Volstad will move into the rotation, and get his first start on Friday against Los Angeles at Dodger Stadium. Hendrickson, meanwhile, will be moved to the bullpen, where he becomes the second lefty option.

A native of Palm Beach Gardens, Fla., Volstad induced a groundout on his first big league pitch, which was a 90-mph fastball to Clint Barmes. His first hit allowed was a single to left by Matt Holliday.

"I was just trying to make pitches," said Volstad, who spent Spring Training with the Marlins and he projected to eventually become a front-line starter for years to come. "At that point, we were down by a run, and I wanted to keep it right there. I was just trying to keep the ball down."

Volstad became the pitcher of record in the sixth inning when the Marlins used a two-run single by Ross to take a 5-4 lead.

With the way the Rockies were scoring runs all series, no lead felt safe. Colorado scored 41 runs in the four games, compared to 38 for Florida.

In the sixth, Volstad experienced his first bases-loaded jam. He worked out of it by getting Barmes to lift a routine fly ball to center.

"He comes in and gets in a jam there with the bases loaded," Gonzalez said. "He gets out of it. It's good for him to get the jitters out, and get in the game. And he got lucky enough to get the victory too."

After Kevin Gregg worked a scoreless ninth inning in a non-save situation, catcher Paul Hoover presented Volstad with the game ball. His teammate, Joe Nelson, greeted him with a shaving cream pie to the face.

In this bizarre series, there was a streak where every inning the Marlins scored through three games and even into Sunday, the Rockies responded with a run in the same frame. That stretch was 10 innings before it was snapped in the third.

So just to get one victory in an otherwise rough long weekend was a relief.

"You're thinking, 'Now you've lost three games in a row, and you are facing their best pitcher," Gonzalez said. "And we go out and beat them. That's why this game is great. We had a chance to win two games late, and that didn't happen. Today, we came out, swung the bats, made some pitches when we had to, and we don't have to see Colorado [at Coors Field], unless we see them in the playoffs or next year."